Direct positive photographs using hydrazine in the emulsion



Patented Mar. 11, 1952 2,588,982 DIRECT POSITIVE PHOTOGRAPHS USING HYDRAZINE IN THE EMULSION Charles E. Ives, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application October 26, 1950, Serial No. 192,380

3 Claims. (01. 95-88) This invention relates to photography and particularly to a method of making direct positive photographs.

In Fallesen U. S. Patent 2,497,875, a method is described for making direct positive photographs with an internal latent image type emulsion by developing the exposed emulsion in an aerial fogging developer with access of oxygen.

I have now found a method for developing direct positive images in an exposed internal latent image emulsion, which method is simpler and more convenient than that described in the Fallesen patent, and which uses a developer not containing formaldehyde; the developer therefore, has better keeping properties than developers hitherto used for this purpose. In addition, the method which I propose to use does not require the addition of oxidizing agents to the developer or any special aeration technique for production of the positive image.

According to my invention the internal latent image emulsion is exposed and then developed in a silver halide developing solution in the presence of a hydrazine compound of the general formula the emulsion. Since hydrazines are reactive with aldehyde type compounds it is undesirable to use aldehyde, such as formaldehyde, for hardening purposes, in emulsions containing hydrazines.

The photographic emulsion used in the process of my invention is a gelatino-silver halide emulsion such as a silver bromide emulsion, a silver bromoiodide emulsion or a silver chloroiodide emulsion. It need not contain optical sensitizing dyes although certain sensitizing dyes may be added to it for the purpose of optical sensitizing or for promoting reversal. The emulsion should be undigested or if digested, the digestion should be carried out without the use of sulfur sensitizers. An emulsion of this type is that known as Burtons emulsion. described in Wall. Photo- 'mately 40% of the content of silver halide.

graphic Emulsions, 1929, pages 52 and 53. Burton's emulsion is made as follows:

Silver nitrate g 100 Water "cc-.. 500 Ammonia-4 0 form clear solution.

Potassium bromide g 80 Potassium iodide g Soft gelatin g 20 Water cc 1000 Dry gelatine g- 250 B is heated to C. and A, cold, added to B with constant shaking, digested for 20 minutes at 50 C., and allowed to cool slowly. C is added after being allowed to swell for 20 minutes in water, drained and melted. The emulsion is then set and washed.

An internal latent image emulsion, that is, one which forms the latent image mostly inside the silver halide grains, as described on pages .296 and 297 of Mees The Theory of the Photoraphic Process, 1942, is especially useful for the process of my invention.

Most of the internal latent image emulsions are silver bromo-iodide emulsions of high iodide content, preferably containing at least 10 %20% of iodide. Burtons emulsion is an emulsion of this type, having a silver iodide content of approxi- It is not absolutely essential, however, for the emulsion to contain silver iodide.

An internal latent image emulsion made as described in Davey and Knott U. S. application Serial No. 82,914, filed March 22, 1949, may also be used according to my invention. This emulsion is prepared by first forming in the absence of ammonia and in one or more stages silver salt grains consisting at least partly of a silver salt which is more soluble in water than silver bromide, subsequently converting the grains to silver bromide or silver bromoiodide and if the silver iodide content of the emulsion is less than 6% calculated on the total silver halide, treating such grains with an iodine compound to bring the silver iodide up to at least 6%, ripening preferably in the absence of ammonia and then either washing out some of the soluble salts or washing out the whole of the soluble salts, followed by the addition of soluble salts such as soluble chloride 3 v 4 or bromide. An example of an emulsion made in The following hydrazine compounds are suitthis way is as follows: able for use according to my invention:

Solution No. 1

Solution No. 2

KCl 100 grams Water 520 cc. W

Solution No. 3

AgNOs 195 grams Water 520 cc.

Solution No. 4

KBr 160 grams Kl 40 grams at 45 C. Water 500 cc.

Run Solutions Nos, 2 and 3 simultaneously into Solution No. 1 in a vessel, taking 90 seconds to do this. Then ripen for 1 minute at 45 C. Next add Solution No. 4, then ripen for 20 minutes at 45 C. Next add 235 grams of inert gelatine (dry) Then ripen at 45 C. for 15 minutes during which time the gelatine dissolves. Set and shred the emulsion and then wash until free from all soluble bromide and then add about 150 cc. of 10% solution of KCl (by Weight), and then add Water to make 3. litres.

An internal latent image type of. silver halide emulsion may be defined as one which,.. when a test portion is exposed to a light intensity scale for a fixed time between 1/100 and 1 second, and developed for 4 minutes at 20 C. in the ordinary, surface developer (Example I), exhibits a maximum density not greater than 1/5 the maximum density obtained when the same emulsion is equally exposed and developed for 3 minutes at 20 C. in an internal type developer (Example II). Preferably the maximum density obtained with the surface developer is not greater than 1/10 the maximum density obtained when the same emulsion is developed in the internal type developer. Stated conversely, an internal latent image emulsion, when developed in an internal type developer (Example II) exhibits a maximum density at least 5, and pref,- erably at least 10, times the maximum density obtained when the same emulsion. is.exposed in the same way and developed in a surface developer. (Example I).

My process is carried out by exposing the internal latent image emulsion layer to an object or image and then placing the'exposed emulsion layer directly in a silver halide developing solution containingone or more of the hydrazine compounds, or if the hydrazine compound i incorporated in the emulsion, byplacing the exposed layer .in the developing solution without the' hydrazine compound. Developing agents suitable for use in the process of my invention include the usual. phenolic or aminophenol type developing agents, such as N-methyl-p-aminophenol sulfate, p-benzohyd'roquinone, catechol, 2-methyl hydroquinone, .zrchlorohydroquinone, p-aminophenol, and pyrogallol. If the hydra-'- zine compound is in the developing solution, the developing solution should have a pH offrom lO to 13, depending upon the degree of activity of the particular hydrazine compound which ,it contains, although the preferred range with most hydrazine compounds is from pH 11 to pI-Il2.-'

NHz--NHz-2HC1 Hydrazine dihydrochloride NHNH2-HC1 Plienylhydrazinc hydrochloride p-Bromphenylhydrazine hydrochloride p-Chlorpheny'lhydrazine hydrochloride 2,5-Dichlorophenyl hydrazine om-Q-zvmmm-ncx p-Tolyl hydrazine hydrochloride H3 -s ogNn mn p-Toluene sulfonyl hydrazine p-Acetylphenylhydrazine Hydrazobcnzene p-Hydrazinobenzoic acid Y Nasce- NH-NH2 p-Hydrazinobenzenesulfonicaciddsodium salt) NH- ivni S O zNa A Phen lhydrazineTm-sulfonic acid (sodium salt I 'caasomnonzom gn'nivm p-lp-(methylsulfonamld-o)ethyl] plienylhydrazine on3so,NH--Nn-ivmnci p Methylsulfonamido-phenylhydrazine hydrochloride CeHs CuHr-P-CHzC ONHNH:

(55H, Cl Triplienyl phosphoniu n chloride acetohydrazide O ONHNH:

o 01mm.

Diamino biuret of omo ONHNH-O B-Phenyl acetliydrazido pyridinium chloride Addition product of phenyl hydrazine and 1-p1ienyl3- hydroxy-fS-pyrazolone of probable structure shown N,N-diphenyl hydrazine p-Diphenyl hydrazine p,p'-dihydrazinodiplienyl-dihydrochloride 1TH C ON HNH:

ll C ONHNH:

d-p-Piienylene disemicarbazidc Example I p l lydroxyphenylglycine g Sodium carbonate (crystals) -g- 100 Water to "liter" 1 Development time, 4 min. at C.

An internal type-developer, that is, one which develops an image inside the grains of an internal latent image emulsion, is the following:

Example II Hydroquinone -e g 15 Monomethyl-p-aminophenol sulfate g 15 Sodium sulfite (anhydrous) g 50 Potassium bromide g- 10 Sodium hydroxide g Sodium thiosulfate (crystals) g- 20 Water to liter. 1

Development time, 3 min. at 20 C.

ErampZeIII An emulsion made as described in the Davey and Knott application Serial No. 82,914 was coated on a support, dried and exposed on an intensity scale sensitometer to 3000 Kelvin tungsten illumination and developed for 3 minutes at 70 F. in a solution of the following composition:

N-methyl-p-aminophenol sulfate g 5 Hydroquinone g 10 Sodium sulfite (desiccated) g Sodium metaborate g.. 30 Sodium hydroxide -g-.. 10 Phenyl hydrazine. hydrochloride g 0.5 Water to. liter-- 1 With these developing conditions a direct positive image of satisfactory characteristics was obtained. A similar development using the same developing solution to which was added 0.2 g. per liter of 5-methyl benzotriazole also produced a satisfactory image although with no improvement in image development of unexposed areas.

In most cases, S-methyl benzotriazole and similar compounds can be added to the developing solution without essentially modifying the resulting image. However, in one case, using ptoluene sulfonyl hydrazine, no reversal was obtained when the 5-methy1 benzotriazole was added to the developer. In some cases the reversal was weakened by adding the benzotriazole; In other cases the maximum density was increased by addin 5-methyl benzotriazole to the developer, for example, with phenyl hydrazine or p- [e- (methylsulfonamido) ethyl] -phenyl hydrazine.

The incorporation of the hydrazine compound in the emulsion is illustrated by the following examples:

Example IV To the amount of a chloro-bromoiodide emulsion made as described in the Davy & Knott application, Serial Number 82,914, containing 108 gms. of silver, there was added 2 gms. of pmethyl-sulfonamido phenyl hydrazine hydrochloride as a 1% solution in methyl alcohol at 40 C., and the mixture was coated on a documentary photographic paper support at the rate of 600 square feet per mole of silver. The paper was dried in the usual way and was exposed on an intensity scale sensitometer to 3000 Kelvin tungsten illumination and was developed for seconds at 75 F. in a solution of the following composition.

N-methyl-p-amino-sulfate gms 5 Hydroquinone gms 10 Sodium sulfite (desiccated) gms 75 Sodium phosphate gms- 75 Sodium hydroxide gms 12 Benzotriazole gms 0.2 Water to liter 1 A direct positive image of satisfactory characteristics was obtained.

Example V An emulsion was prepared and coated in the same way as described in Example IV except that 2 gms. of p-[B-(methyl-sulfonamido) ethyl] phenyl hydrazine was used instead of the hydrazine named in Example IV. This paper was dried as usual and exposed and developed as in 7 Example IV. A direct positive image of satisfactory characteristics was obtained.

Although the reversal effect obtained in my process does not require agitation of the developer or the presence of oxidizing agents, I believe that the fogging action obtained is related to aerial oxidation. The active agent, which is derived from the hydrazine compound appears to have along life in the developing solutions and only brief exposures to atmospheric oxygen appear suflicient to produce fogging even in the absence of continued aeration. My process, therefore, has distinct advantages for deep tank photographic processing. v

This application is a continuation-in-part of my application Serial No. 159,150, filed April 29, 1950, now Patent No. 2,563,785 of August 7, 1951.

It will be understood that the examples and modifications included herein are illustrative only and that my invention is to be taken as limited only by the scope of the appended claims.

I claim:

l. The method of obtaining a direct positive image in a silver halide emulsion layer, which comprises exposing to light rays to which the emulsion is sensitive, a silver halide emulsion layer a test portion of which upon exposure to a light intensity scale for a fixed time between $4 and 1 second and development for 3 minutes at 20 C. in the following internal type developer (II) Grams Hydroquinone 15 Monomethyl-p-aminophenol sulfate l5 Anhydrous sodiumsulfite 50 Potassium bromide Sodium hydroxide 25 Sodium thiosulfate 20 Water to 1 liter gives a maximum density at least 5 times the maximum density obtained when the equally exposed silver halide emulsion is developed for 4 minutes at 20 C. in the following surface developer (I) Grams p-Hydroxyphenylglycine 10 Sodium carbonate 100 Water to 1 liter said emulsion containing a hydrazine compound of the general formula where R, is a mononuclear aryl radical, and developing only the unexposed portion of said emulsion layer in a silver halide developer. I h

2. The method of obtaining a direct positive image in a'silver halide emulsion layer, -which comprises exposing to light rays to which the emulsion is sensitive, a silver halide emulsion layer a test portion of which upon exposure to a light intensity scale for a fixed time between and 1 second and development for 3 minutes at 20 C. in the following internal type developer (II):

Grams Hydroquinone 15 Monomethyl-p-aminophenol sulfate 15 Anhydrous sodium sulfite 50 Potassium bromide 10 Sodium hydroxide 25 Sodium thiosulfate 20 Water to 1 liter gives a maximum density at least 5 times the maximum density obtained when the equally exposed silver halide emulsion is developed for 4 minutes at 20 C. in the following surface developer (I):

Grams p-Hydroxyphenylglycine 10 Sodium carbonate Water to 1 liter said emulsion containing p-methyl-sulfonamidophenyl hydrazine hydrochloride, and developing only the unexposed portion of said emulsion layer in a silver halide developer.

3. The method of obtaining a direct positive image in a silver halid emulsion layer, which comprises exposing to light rays to which the emulsion is sensitive, a silver halide emulsion layer a test portion of which upon exposure to a light intensity scale for a fixed time between and 1 second and development for 3 minutes at 20 C. in the following internal type deve1- oper (II):

Grams Hydroquinone 15 Monomethyl-p-aminophenol sulfate 15 Anhydrous sodium sulfite 50 Potassium bromide 10 Sodium hydroxide 25 Sodiumthiosulfate 20 Water to 1 liter 7 gives a maximum density at least 5 times the maximum density obtained when the equally exposed silver halide emulsion is developed for 4 minutes at 20 C. in the followin surface developer (I):

Grams p-Hydroxyph'enylglycine 10 Sodium carbonate 100 Water to 1 liter said emulsioncontaining p-[p-(methylsulfonamido)ethyll ,phenyl hydrazine, and developing only the unexposed portion of said emulsion layer in a silver halide developer. f

CHARLES E. IVES.

REFERENCES CITED The following references are of record in the. file of this patent:

UNITED STATES PATENTS Number Name Date 2,563,785 Ives Aug. 7, 1951 

1. THE METHOD OF OBTAINING A DIRECT POSITIVE IMAGE IN A SILVER HALIDE EMULSION LAYER, WHICH COMPRISES EXPOSING TO LIGHT RAYS TO WHICH THE EMULSION IS SENSITIVE, A SILVER HALIDE EMULSION LAYER A TEST PORTION OF WHICH UPON EXPOSURE TO A LIGHT INTENSITY SCALE FOR A FIXED TIME BETWEEN 1/100 AND 1 SECOND AND DEVELOPMENT FOR 3 MINUTES AT 20* C. IN THE FOLLOWING INTERNAL TYPE DEVELOPER (II): 